As compared to other display devices, the organic light emitting diode (OLED) display devices are thinner and lighter, and having lower power consumption and lower cost. Typically, the OLED display device also has higher brightness, wider viewing angle, higher contrast, and higher flexibility.
An OLED display device includes an array substrate having an OLED disposed thereon. The first electrode (typically the cathode) is typically a plate electrode covering the array substrate. Usually, the first electrode is made of conductive metals such as magnesium or silver. Because light emits from the first electrode in a top emitting OLED, it requires a first electrode having a high transmission rate. Thus, the first electrode is often manufactured as a very thin layer having high resistance. Consequently, the IR drop of the first electrode is relatively large, resulting in a non-uniform image display.